1. Field of the Invention
This invention relates to a suction device for cutting wastes in a cryostatic microtome, and more particularly to an arrangement for disinfecting and sterilizing the air stream of the suction device.
2. Discussion of Relevant Prior Art
A suction device for cryostatic microtomes is known from U.S. Pat. No. 5,255,585, in which at least a first filter is arranged in the internal space of the cryostat. The cutting wastes arising during cutting are trapped by this first filter and are stored in the frozen state, corresponding to the cryostat temperature, at temperatures in the region between -10.degree. C. and -40.degree. C. A bacteriological filter can optionally be connected after this filter, to retain microscopic particles which pass through the first filter, before the exhaust air of the suction device is delivered to the atmosphere. It is a disadvantage in this system that substantially warmer outside air is permanently exchanged for the cooled air in the cryostat. To maintain a stable cryostat temperature, in particular in the low temperature region, a considerable cooling power of the cryostat is therefore required.
It is furthermore disadvantageous that the air delivered from the suction device into the surroundings is in fact filtered and is also partially freed from bacteria by the use of a bacteriological filter, but nevertheless an effective disinfection of the exhaust air cannot be attained by mechanical cleaning.
A further suction device for cryostatic microtomes is offered by Microm Laborgerate GmbH under the name "Vacutome". This suction device has, inside the cryostat, a container with a paper filter to trap the cutting waste. In contrast to U.S. Pat. No. 5,255,585, this suction device works according to the principle of circulation, i.e., after mechanical cleaning by the paper filter, the air stream of the suction device is conducted back into the cryostat. A large introduction of outside air into the cryostat is thereby avoided. However, in this case also, a complete, or nearly complete, sterilization of the air stream does not take place. Thus contamination of the air in the cryostat, and hence an enrichment of the specimen to be cut with disease sources, can take place here. Apart from this, contaminated air is also released to the surroundings on opening the cryostat.